Method of forming electrical contacts



May 3, 1938.- s. KoEszYl 2,115,269

` METHOD OF FORMING ELECTRICAL CONTACTS Filed Jan. 18, 1957 2Sheets-Sheet 2 www Patented May 3, 1938 NUNITED STATES PATENT OFFICEMETHOD OF FORMING ELECTRICAL CONTACTS Claims.

The primary object of this invention is to provide an improved methodfor producing electrical contacts from strips of sheet metal through aseries of operations which will involve less time and less waste ofmaterial. This is accomplished by utilizing a series of spacedstationary dies and registering, punching, forming and embossing diescarried -by the stationary and movable jaws, respectively, of a punchpress, and so arranged that a strip of sheet metal advanced apredetermined distance at each actuation of the punch press will formthe contact by a series of operations of the dies. This strip may be fedb-y hand or mechanically.

A mechanism suitable for carrying out this invention is fully describedin the following specification in conjunction with the accompanyingdrawings wherein:

Figure 1 is a perspective of one end of a metal strip indicating theseveral operations to which the strip is subjected as it advancesendwise, a completed contact being shown as severed from the forward endof the strip;

Fig. 2 is a plan view partly in sectiononline 2-2 of Fig. 3 showing thevarious punching, forming, notching, shearing, and embossing dies usedin forming this electrical contact from a strip of sheet metal; v

Fig. 3 is a partial vertical section on broken line 3-3 of Fig. 2;

Fig. 4 is a partial vertical section on line 4-4 of Fig. 2 showing aslitting die;

Fig. 5 is a partial vertical section on line 5 5 of Fig. 2 showing aforming die in operation;

Fig. 6 is a partial section on line 6-6 of Fig. 2 showing two formingdies in operation simultaneously;

Figs. 7 and 8 are two partial sections on lines I-l and 8 8,respectively, of' Fig. 2, showing forming dies in operation, Fig. 8 alsohaving an embossing die operating simultaneously therewith; and

Fig. 9 is an enlarged perspective of the finished electrical contact.

The electrical contact for which my improved method of production hasbeen devised is such as may advantageously be-employed to receiveengagement from one of the prongs of a vacuum tube. As shown best inFig. 9, this contact C is made of sheet metal having requisite springprop-V (Cl. zei-4155.55)

the terminal lug, is a clip c whose angled 4body is sufllciently wide toprovide for turned sides c and c2 which face each other whereby to gripbetween them and the clip body, the prong (not shown) of a vacuum tubeor other electrical instrument. Ears d may be extended outwardly fromthe clip sides at a point adjacent the mounting plate, as shown. l

The mechanism illustrated for punching and forming this contact from astrip of metal comprises a series of dies, the stationary element ofeach die being carried by the stationary jaw ill of a conventional punchpress while the movable members are carried by its movable jaw Il.Inasmuch as a punch press is well known, further ydescription thereof isunnecessary. It is understood, however, that at each actuation of thepunch press the movable jaw II descends a predetermined distance towardthe stationary jaw III and then returns to its initial position whereinall of the movable parts ofthe die are above the strip.

Two punches I2, I3 which are preferably round pass through suitableguides I4 and coact with registering openings I5, I6 in a die block I1which is carried by the stationary jaw IIJ to form the holes b', b2. Theguide I4 is separated from the die block I1 leaving a passage I8 throughwhich the metal strip S may be fed endwise either manually, or by meansof mechanism not shown, a definite amount at each step. The sides ofpassage I8 serve also to guide the strip laterally, or, if desired,other guide means may be used.

A punch I9 which is secured to the movable x jaw II coacts with acorresponding opening in the die block. This latter punch is preferablyrectangular in form with a recessed portion which leaves an ear 20.

At the next operation, when the strip has been advanced toward the leftside of the sheet one step, the ear is slitted centrally along the line2| by means of a punch 22, as shown in Fig. 4, to form the ears d. Atthe vsame time a notching punch 23 the center of which is preferably inline with the line 2l removes a portion of the left side of the strip soas to outline a portion of the lugs b of the finished contacts b utleaving a narrow bar 24 to connect adjacent contact blanks. For the sakeof convenience, the upper edge of the strip S (Fig. 2) is referred ltoas the right side and the lower as the left` side.

At the next stage, and when the strip has been advanced one space, thefirst forming punch 25 serves to bend down the slitted ears 20 to theposition 20'. The lower end of this punch is rounded to serve as a pilotpunch for the entire group.

The second forming punch 26 coacts with a stationary forming die 21, asshown in Fig. 3 to cause the parallel slitted portions 28 to be bentvertically into the position 28'. A plunger 28 is slidably mounted inthe block 21 and is pressed by means of a spring 30, the spring restingupon a screw 3|. This spring is suillciently strong to force the edgeportions 28' out of the die block 21 as the punch 26 recedes. It will beobserved also that the upper surface of the die block 21 is slightlyraised. so that as the strip is advanced it slides up over the surface21. Another forming punch 32 serves to curve the lug b as shown in Fig.6 on the curved die surface 21h. As the strip is again advanced onestep, the edge portions 28* of the right hand end -are engaged by athird forming punch 33 whose lower surface is provided with a V-notchv34. As the forming punch 33 descends it presses the right hand end ofthe contact down against a stationary block 35 and, as it continues todescend, forces the edges 28* inwardly from the dotted line position tothe full line position 28h, as shown beneath lthe punch 33 completingthe clip c.

The block 35 is provided with a spring pressed plunger- 36 similar tothe plunger 29. During this forming operation the plunger 36 is presseddown, as shown, against the action of a spring 31, but as soon as thedie rises, the spring 31 will push the plunger 38 up, lifting the righthand end of the formed contact out of the block 35.

As the strip is advanced one more step it reaches the position shown bythe section line 1-1 of Fig. 2 wherein the right hand end falls beneatha fourth forming punch 38 .which passes between the inwardly bent edges28h and bends the clip c down over a ledge 39 until it assumes aposition 28e substantially at right angles to tionary ledge 40 by meansof a fth forming punch 4| carried by the movable jaw Il. At the sametime the body oi' the contact is embossed to form the button b3 by meansof an embossing punch 42, as shown in Fig. 3,'cooperating with adepression 43 in a stationary die 44 which carries the ledge 40.

At the same time the finished contact C is completed by means of a shear45 which cuts away the bar 24 connecting the last contact with the nextadjacent contact as indicated by the dotted lines 24.

According to the method of procedure herein described, the contacts inquestion may be produced economically as regards the material used andthe time consumed.

I claim:

l. The method of forming contacts of the class described from a sheetmetal strip comprising arranging a series of punching and forming diesin spaced alignment, the steps in order comprising punching the leftside of the strip in what is later one end of the contact, punching outan intermediateportion midway to outline portions of two contactsleaving therebetween an inwardly extending ear, slitting from the rightedge of the strip through said ear, notching the left side of the strip.passing a f tact from each other, and severing the last contact from thestrip.

2. The method of forming contacts of the class described'from a sheetmetal strip comprising arranging a series of punching and forming diesin spaced alignment, the steps in order comprising punching the leftside of the strip in what is later one end of the contact, punching outan intermediate portion midway between two contacts leaving therebetweenan inwardly extending ear, slitting from the right edge of the stripthrough said ear, simultaneously notching the left side of the strip,passing a forming die through the punched opening in the intermediateportion to bend down the slitted ear, bending up two slitted portionsfrom the right side of the strip including said ears, bending said por-'tions toward each other, bending the right hand end of the contactabout a first line parallel to the edge of the strip, bending the righthand end of the strip about a second line parallel to the first line andat the left thereof so as to space the two end portions of the contactfrom each other,

and severing the last contact from the strip.

3. The method of forming contacts of the class described from a sheetmetal strip comprising arranging a series of punching and forming diesin spaced alignment, f the steps in order comprising punching the leftside of the strip in what is later one end of the contact, punching outan intermediate portion midway between two contacts leaving therebetweenan inwardly extending ear, slitting from the right edge of the stripthrough said ear, notching the left side of the strip, passing a formingdie through the punched opening in the intermediate portion to bend downthe slitted ear, bending up two slitted portions from the right side ofthe strip including said ears, simultaneously bending up the left handend of the contact, bending said portions toward each other, bending theright hand end of the strip about a second line parallel to the firstline and at the left thereof so as to space the two end portions of thecontact from each other, and severing the last contact from the strip.

4. The method of forming contacts of the class described froma sheetmetal strip comprising arranging a series of punching and forming diesin spaced alignment, the steps in order comprising punching the leftside of the strip in what is later o'ne end of the contact, punching outan intermediate portion midway between two contacts leaving therebetweenan inwardly extending ear, slitting from the rightedge of the stripthrough said ear, notching the left side of the strip passing a formingdie through the punched opening in the', intermediate portion to benddown the slitted ear, bending up two slitted portions from the rightside of the strip including said ears.' simultaneously bending up theleft hand end of the con- 7 left thereof so as tnspace thel two endportions u of the contact from each other, embossing, and

`severing the last contact from the strip.

5. The method of forming contacts o f the class described from a sheetmetal strip comprising arranging a series of punching and forming out anintermediate portion midway between two contacts leaving therebetween aninwardly extending ear, slitting from the right edge ot the stripthrough said ear, notchingthe left side of` the strip so as to leaveonly n. narrow bar connecting the adjacent contacts, passing a formingdie through the punched opening in the intermediate portion to bend downthe slitted ear, bending up two slitted portions from the right side ofthe strip, bending said portions toward each other, bending the righthand end 'of the contact about a iirst line parallel to the edge of thestrip, bending the right hand end of the strip about a second lineparallel to the iirst line and at the left thereof so as to space thetwo lend portions oi the contact from each other, and cutting out theconnecting bar thereby severing the last contact from the strip.

STEVEN KOBZY.

